Air duct standard
1.1.1 Application Scope
This construction technical standard is applicable to the processing and production of metal, non-metal and composite air ducts or air ducts used in ventilation and air conditioning engineering of building projects.
1.1.2 Compilation of reference standards and specifications
(1) National Standard of the People's Republic of China "Ventilation and Air Conditioning Engineering Construction Quality Acceptance Code" (GB 50243-2002)
(2) The National Standard of the People's Republic of China, Unified Standard for Acceptance of Construction Quality of Building and Installation Engineering (GB 50300-2001)
1.2 Terminology 
(1) Inspection batch: an inspection body composed of a certain number of samples which is collected for inspection under the same production conditions or in a prescribed manner.
(2) Inspection: The performance of the inspection items shall be measured, inspected, tested, etc., and the results shall be compared with the requirements specified in the standard to determine whether each performance is qualified.
(3) Handover inspection: Both the undertaking party and the completion party shall check and confirm whether the construction can continue.
(4) Main control items: inspection items in construction projects that play a decisive role in safety, health, environmental protection and public interests.
(5) General items: inspection items other than the main control items.
(6) Sampling inspection: According to the stipulated sampling scheme, a certain number of samples are randomly selected from the inspection items of materials, components, equipment or construction engineering in the approach according to the inspection batch.
(7) Air duct: a pipe made of metal, non-metal sheet or other materials for air circulation.
(8) Air duct: made of concrete, brick and other building materials, used for air circulation channel.
(9) Ventilation engineering: air supply, air exhaust, dust removal, pneumatic conveying and smoke prevention and exhaust system engineering.
(10) Air conditioning engineering: air conditioning, air purification and clean air conditioning system.
(11) Bite: the edge of the metal sheet is bent into a certain shape for the structure of mutual fixed connection.
(12) Air leakage: the volume of air discharged or infiltrated per unit time in the air duct system through the air duct body structure and its interface under a certain static pressure.
(13) Allowable air leakage of the system air duct: maximum allowable air leakage of the average unit area and unit time according to the category of the air duct system.
(14) Air leakage rate: the ratio of air infiltration or leakage of air conditioning equipment and dust precipitator to its rated air volume under working pressure.
(15) Purification air conditioning system: used for clean space air conditioning, air purification system.
(16) Light leakage detection: light transmission inspection is carried out on the bite, seam, flange and other joints of the air duct with strong light source to determine the leakage parts and the number of holes, gaps and other methods.
(17) Working pressure of the air duct system: refers to the maximum working pressure designed at the main air duct of the system.
(18) Air cleanliness class: A class standard divided by the maximum concentration limit of particles greater than or equal to the considered particle size in the air per unit volume of clean space.
(19) Corner member: a rectangular special member used for connecting the four corners of the metal sheet steel flange air pipe.
(20) Non-metallic material air duct: Air duct made of hard polyvinyl chloride, organic glass steel, inorganic glass steel and other non-metallic inorganic materials.
(21) Composite material air duct: Air duct made of non-combustible material surface layer composite insulation material board.
(22) Fireproof air duct: made of non-combustible and refractory materials, which can meet certain fire resistance limits.